U.S. Environmental Protection Agency (EPA) employs 17,000 people across the country, including our headquarters offices in Washington, DC, 10 regional offices, and more than a dozen labs. Our staff are highly educated and technically trained; more than half are engineers, scientists, and policy analysts. In addition, a large number of employees are legal, public affairs, financial, information management and computer specialists.

http://www.epa.gov/epahome/aboutepa.htm

The U.S. Environmental Protection Agency on wikipedia:http://en.wikipedia.org/wiki/United_States_Environmental_Protection_Agency

Indoor Environmental Quality

NIOSH Safety and Health Topic

http://www.cdc.gov/niosh/topics/indoorenv/